1. Field of the Invention
This invention relates to a control of a rotational angular position of a circular table by the use of an absolute position detector.
2. Description of the Prior Art
The conventional systems for controlling the rotational angular position of a circular table include two types; one using an incremental position detector and the other an absolute one. In the case of a power failure in the course of work or when the power supply is cut off due to a suspension of work, the control apparatus of the former system is unable to remember the present position of the circular table. At the time of resumption of work, therefore, the circular table has to be inconveniently returned to the origin. Another disadvantage of this sytem is that an angular command requires a special position detector for angular detection. On the other hand, the latter system has a disadvantage in that numerical values detectable by a position detector have a limitation, thus limiting the rotation of the circulation table in the same direction and the programming practice on the other.